How bad would the rubbing be if I were to get 37x13.50x20 Mud Grapplers on 20x9 XD Spy's? The Spys have a 4.53" backspacing. And I would also like to know how bad it would be if I got 37's and didn't regear.

My Fabtech 6" lift is in the mail so the sooner you could reply the better.

I'm not saying I will never regear, but I just don't have the money right now.

 

I'd say that combo is gonna rub pretty bad unless you add at least a leveling kit, or you crank up the preload on the coilovers (if you have the optional Dirt Logics).
Your performance may be livable if you have the 5.4, 3.73 gears and don't do any towing/hauling.